The invention relates to an apparatus for the mass transfer between two media, for example, for the dialysis of blood relative to a dialysis liquid. The apparatus comprises a housing containing a core surrounded by hollow fibers. The housing further contains for each of the two media one influx chamber and an out-flow chamber, whereby one ring shaped chamber each is operatively connected to the two facing ends or rather, with the openings of the hollow fibers.
Heretofore, known devices of the mentioned type exhibit the disadvantage that there is an increased tendency for the coagulation of the blood, that the distribution of the blood flow onto the individual hollow fibers is non-uniform, and that the wash contact of the dialysis solution with the individual hollow fibers is also non-uniform. A non-uniform distribution of the flow through the hollow fibers as well as a non-uniform wash contact of the hollow fibers with the dialysis solution result in a decrease of the exchange efficiency relative to the theoretically possible exchange efficiency. It is possible to compensate for such decreased exchange efficiency to a certain extent by increasing the through flow of the dialysis solution. However, such increase of the through flow results in an increase consumption of dialysis solution or it requires an additional technical effort for the recirculation of the dialysis solution. A non-uniform distribution of the through flow of blood causes the coagulation of the latter because the blood tends to coagulate preferably in those hollow fibers in which it flows more slowly. Similar disadvantages occur in mass exchange devices constructed for different purposes.